Continuous casting in the production of steel and other metals is well known in the art.
The continuous casting operations of the prior art have not been without considerable problems, however, especially in the slab cutting area. One technique of the prior art is the use of descending rollers on the roller table. This technique has several drawbacks, however. During the cutting process slag is generated, which sticks to rollers and mechanisms used in the slab conveying operation, which eventually cuts into the rollers and mechanisms slowing, if not halting, operation. In general, this type of slab cutting operation requires complicated hydraulic lifting and lowering devices which are costly and require considerable maintenance. Additionally, this type of slab cutting technique for continuous casting requires the control of lowering rollers according to the cutting/synchronous travel progress of the cutting means being used. Furthermore, granulation of the slag in the cutting area is necessary.
A major problem of the prior art systems is the inability to adequately remove smoke and gases generated by the slab cutting process, especially in multiple strand casting plants. Furthermore, the resulting difficult visibility of the kerf surface makes it difficult for the operator to assess problems in the cutting operation and take corrective action. Also, the need for large gaps in the support mechanisms for the slab occasionally limit the minimum piece length that can be obtained. The above problems are typically found in the area including the descending rollers in the roller table.
Another known cutting method uses a roller or disc roller table with intermittent cutting (that is no cutting over the rollers or roller shafts). This type of cutting operation is likewise fraught with problems, including the tendency for slag to stick to the rollers and cut into the rollers with eventual operational failures. Often slag granulation occurs fairly close to the roller. Also, the synchronous controller for the cutting device pauses over the rollers, requiring a longer cutting area to compensate for the pause in cutting when the cutting device is positioned over the rollers. These repeated cutting starts and stops result in poor cut surface quality and present a risk of disruptions in the cutting process. Additionally, insufficient smoke removal, as previously described, especially at variable strand widths and difficult visibility of the kerf surface are common in this strand cutting method.
In another slab cutting device of the prior art, a moving roller table with or without cut interruption over the slab rollers uses a variable drive mechanism which attempts to pass the slab being cut at a faster rate when the cutting mechanism passes over a roller. This device requires complex drive mechanisms and variable distances corresponding to the location of roller supports at the entrance or exit of the roller table. Additionally, all of the disadvantages of the other prior art cutting systems are present, even if slag occurrence, increased cutting time or increased synchronous travel path are improved relative to the intermittent cutting method.
Accordingly, it would be useful in the art of continuous casting to develop a slab cutting device/roller table that alleviates or solves many or most of the aforedescribed problems of prior art systems.